/* CSS Variables for theming */
:root {
  --color-white: #FFFFFF;
  --color-light-gray: #F8F9FA;
  --color-medium-gray: #E9ECEF;
  --color-border-gray: #DEE2E6;
  --color-dark: #212529;
  
  /* Theme colors */
  --bg-primary: var(--color-white);
  --bg-secondary: var(--color-light-gray);
  --bg-card: var(--color-white);
  --text-primary: var(--color-dark);
  --text-secondary: #6C757D;
  --border-color: var(--color-border-gray);
  --shadow: 0 2px 10px rgba(33, 37, 41, 0.1);
  
  /* Accent colors */
  --color-primary: #007BFF;
  --color-success: #28A745;
  --color-warning: #FFC107;
  --color-danger: #DC3545;
  --color-info: #17A2B8;
  
  /* Transitions */
  --transition: all 0.3s ease;
  
  /* Typography */
  --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-size-xs: 0.75rem;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.25rem;
  --font-size-2xl: 1.5rem;
  --font-size-3xl: 2rem;
  
  /* Spacing */
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-2xl: 3rem;
  
  /* Border radius */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
}

/* Dark theme variables */
[data-theme="dark"] {
  --bg-primary: #1a1a1a;
  --bg-secondary: #2d2d2d;
  --bg-card: #242424;
  --text-primary: #ffffff;
  --text-secondary: #b3b3b3;
  --border-color: #404040;
  --shadow: 0 2px 10px rgba(0, 0, 0, 0.3);
}

/* Reset and base styles */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  line-height: 1.6;
  color: var(--text-primary);
  background-color: var(--bg-primary);
  transition: var(--transition);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Container */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-md);
}

/* Header */
.header {
  background-color: var(--bg-card);
  border-bottom: 1px solid var(--border-color);
  padding: var(--spacing-lg) 0;
  box-shadow: var(--shadow);
}

.header__content {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.header__brand {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-xs);
}

.header__title {
  font-size: var(--font-size-2xl);
  font-weight: 700;
  color: var(--color-primary);
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
}

.header__icon {
  font-size: var(--font-size-xl);
}

.header__subtitle {
  font-size: var(--font-size-sm);
  color: var(--text-secondary);
  font-weight: 400;
}

/* Theme Toggle */
.theme-toggle {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: var(--spacing-sm) var(--spacing-md);
  cursor: pointer;
  transition: var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
  min-width: 48px;
  min-height: 48px;
}

.theme-toggle:hover {
  background: var(--border-color);
  transform: translateY(-1px);
}

.theme-toggle__icon {
  font-size: var(--font-size-lg);
  transition: var(--transition);
}

/* Main Content */
.main {
  flex: 1;
  padding: var(--spacing-2xl) 0;
  background-color: var(--bg-secondary);
}

/* Cards */
.card {
  background: var(--bg-card);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow);
  border: 1px solid var(--border-color);
  margin-bottom: var(--spacing-xl);
  overflow: hidden;
  transition: var(--transition);
}

.card:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 20px rgba(33, 37, 41, 0.15);
}

[data-theme="dark"] .card:hover {
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.4);
}

.card__header {
  padding: var(--spacing-lg) var(--spacing-xl);
  border-bottom: 1px solid var(--border-color);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.card__title {
  font-size: var(--font-size-xl);
  font-weight: 600;
  color: var(--text-primary);
}

.card__content {
  padding: var(--spacing-xl);
}

/* Password Display */
.password-display {
  margin-bottom: var(--spacing-xl);
}

.password-output {
  display: flex;
  gap: var(--spacing-sm);
  margin-bottom: var(--spacing-md);
}

.password-output__field {
  flex: 1;
  padding: var(--spacing-md) var(--spacing-lg);
  border: 2px solid var(--border-color);
  border-radius: var(--radius-md);
  font-family: 'Courier New', monospace;
  font-size: var(--font-size-lg);
  background: var(--bg-secondary);
  color: var(--text-primary);
  transition: var(--transition);
  min-height: 56px;
}

.password-output__field:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(0, 123, 255, 0.1);
}

.password-output__copy {
  background: var(--color-primary);
  color: white;
  border: none;
  border-radius: var(--radius-md);
  padding: var(--spacing-md) var(--spacing-lg);
  cursor: pointer;
  transition: var(--transition);
  min-width: 56px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.password-output__copy:hover:not(:disabled) {
  background: #0056b3;
  transform: translateY(-1px);
}

.password-output__copy:disabled {
  background: var(--text-secondary);
  cursor: not-allowed;
  opacity: 0.6;
}

.copy-icon {
  font-size: var(--font-size-lg);
}

/* Strength Indicator */
.strength-indicator {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
}

.strength-indicator__label {
  font-size: var(--font-size-sm);
  color: var(--text-secondary);
  font-weight: 500;
}

.strength-indicator__bar {
  height: 8px;
  background: var(--border-color);
  border-radius: var(--radius-sm);
  overflow: hidden;
}

.strength-indicator__fill {
  height: 100%;
  transition: all 0.5s ease;
  border-radius: var(--radius-sm);
}

.strength-indicator__fill.weak {
  background: var(--color-danger);
  width: 25%;
}

.strength-indicator__fill.medium {
  background: var(--color-warning);
  width: 60%;
}

.strength-indicator__fill.strong {
  background: var(--color-success);
  width: 100%;
}

/* Password Options */
.password-options {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-xl);
}

.option-group {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
}

.option-group__title {
  font-size: var(--font-size-lg);
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--spacing-sm);
}

.option-label {
  font-size: var(--font-size-base);
  font-weight: 500;
  color: var(--text-primary);
}

/* Length Slider */
.length-slider {
  width: 100%;
  height: 8px;
  border-radius: var(--radius-sm);
  background: var(--border-color);
  outline: none;
  -webkit-appearance: none;
  cursor: pointer;
}

.length-slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: var(--color-primary);
  cursor: pointer;
  transition: var(--transition);
}

.length-slider::-webkit-slider-thumb:hover {
  transform: scale(1.1);
  box-shadow: 0 0 10px rgba(0, 123, 255, 0.3);
}

.length-slider::-moz-range-thumb {
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: var(--color-primary);
  cursor: pointer;
  border: none;
  transition: var(--transition);
}

.length-marks {
  display: flex;
  justify-content: space-between;
  margin-top: var(--spacing-xs);
  font-size: var(--font-size-xs);
  color: var(--text-secondary);
}

/* Checkbox Grid */
.checkbox-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--spacing-md);
}

.checkbox-option {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  cursor: pointer;
  padding: var(--spacing-sm);
  border-radius: var(--radius-md);
  transition: var(--transition);
}

.checkbox-option:hover {
  background: var(--bg-secondary);
}

.checkbox-option input[type="checkbox"] {
  display: none;
}

.checkbox-option__checkmark {
  width: 20px;
  height: 20px;
  border: 2px solid var(--border-color);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: var(--transition);
  flex-shrink: 0;
}

.checkbox-option input[type="checkbox"]:checked + .checkbox-option__checkmark {
  background: var(--color-primary);
  border-color: var(--color-primary);
}

.checkbox-option input[type="checkbox"]:checked + .checkbox-option__checkmark::after {
  content: '✓';
  color: white;
  font-size: var(--font-size-sm);
  font-weight: bold;
}

.checkbox-option__label {
  font-size: var(--font-size-base);
  color: var(--text-primary);
  user-select: none;
}

/* Generate Button */
.generate-btn {
  background: linear-gradient(135deg, var(--color-primary), #0056b3);
  color: white;
  border: none;
  border-radius: var(--radius-lg);
  padding: var(--spacing-lg) var(--spacing-xl);
  font-size: var(--font-size-lg);
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-sm);
  box-shadow: 0 4px 15px rgba(0, 123, 255, 0.2);
}

.generate-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(0, 123, 255, 0.3);
}

.generate-btn:active {
  transform: translateY(0);
}

.generate-btn__icon {
  font-size: var(--font-size-xl);
  animation: spin 0.5s ease-in-out;
}

@keyframes spin {
  from { transform: rotate(0deg); }
  to { transform: rotate(360deg); }
}

/* Clear History Button */
.clear-history-btn {
  background: var(--color-danger);
  color: white;
  border: none;
  border-radius: var(--radius-md);
  padding: var(--spacing-sm) var(--spacing-md);
  font-size: var(--font-size-sm);
  cursor: pointer;
  transition: var(--transition);
  display: flex;
  align-items: center;
  gap: var(--spacing-xs);
}

.clear-history-btn:hover {
  background: #c82333;
  transform: translateY(-1px);
}

/* History List */
.history-list {
  max-height: 400px;
  overflow-y: auto;
}

.history-empty {
  text-align: center;
  padding: var(--spacing-2xl);
  color: var(--text-secondary);
}

.history-empty__icon {
  font-size: var(--font-size-3xl);
  margin-bottom: var(--spacing-md);
  display: block;
}

.history-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--spacing-md);
  border-bottom: 1px solid var(--border-color);
  transition: var(--transition);
}

.history-item:hover {
  background: var(--bg-secondary);
}

.history-item:last-child {
  border-bottom: none;
}

.history-item__content {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: var(--spacing-xs);
}

.history-item__password {
  font-family: 'Courier New', monospace;
  font-size: var(--font-size-base);
  color: var(--text-primary);
  word-break: break-all;
}

.history-item__info {
  font-size: var(--font-size-xs);
  color: var(--text-secondary);
}

.history-item__actions {
  display: flex;
  gap: var(--spacing-xs);
}

.history-item__copy {
  background: var(--color-primary);
  color: white;
  border: none;
  border-radius: var(--radius-sm);
  padding: var(--spacing-xs) var(--spacing-sm);
  cursor: pointer;
  transition: var(--transition);
  font-size: var(--font-size-sm);
}

.history-item__copy:hover {
  background: #0056b3;
}

/* Tips Section */
.tips-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
}

.tips-list__item {
  padding: var(--spacing-md);
  background: var(--bg-secondary);
  border-radius: var(--radius-md);
  border-left: 4px solid var(--color-primary);
}

/* Footer */
.footer {
  background: var(--bg-card);
  border-top: 1px solid var(--border-color);
  padding: var(--spacing-lg) 0;
  text-align: center;
}

.footer__text {
  font-size: var(--font-size-sm);
  color: var(--text-secondary);
}

.footer__link {
  color: var(--color-primary);
  text-decoration: none;
  font-weight: 500;
  transition: var(--transition);
}

.footer__link:hover {
  text-decoration: underline;
}

/* Toast Notification */
.toast {
  position: fixed;
  bottom: var(--spacing-xl);
  right: var(--spacing-xl);
  background: var(--color-success);
  color: white;
  padding: var(--spacing-md) var(--spacing-lg);
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  box-shadow: 0 4px 20px rgba(40, 167, 69, 0.3);
  transform: translateX(100%);
  transition: transform 0.3s ease;
  z-index: 1000;
}

.toast.show {
  transform: translateX(0);
}

.toast__icon {
  font-size: var(--font-size-lg);
}

.toast__message {
  font-weight: 500;
}

/* Responsive Design */
@media (max-width: 768px) {
  .container {
    padding: 0 var(--spacing-sm);
  }
  
  .header__content {
    flex-direction: column;
    gap: var(--spacing-md);
    text-align: center;
  }
  
  .header__title {
    font-size: var(--font-size-xl);
  }
  
  .card__header {
    padding: var(--spacing-md);
    flex-direction: column;
    gap: var(--spacing-sm);
    align-items: flex-start;
  }
  
  .card__content {
    padding: var(--spacing-md);
  }
  
  .password-output {
    flex-direction: column;
  }
  
  .password-output__copy {
    align-self: stretch;
  }
  
  .checkbox-grid {
    grid-template-columns: 1fr;
  }
  
  .generate-btn {
    padding: var(--spacing-md) var(--spacing-lg);
    font-size: var(--font-size-base);
  }
  
  .history-item {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--spacing-sm);
  }
  
  .history-item__actions {
    align-self: stretch;
    justify-content: flex-end;
  }
  
  .toast {
    bottom: var(--spacing-md);
    right: var(--spacing-md);
    left: var(--spacing-md);
  }
}

@media (max-width: 480px) {
  .main {
    padding: var(--spacing-lg) 0;
  }
  
  .card {
    margin-bottom: var(--spacing-lg);
  }
  
  .header__title {
    font-size: var(--font-size-lg);
  }
  
  .card__title {
    font-size: var(--font-size-lg);
  }
}

/* Accessibility improvements */
@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* Focus styles for keyboard navigation */
button:focus-visible,
input:focus-visible,
.checkbox-option:focus-within {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

/* High contrast mode support */
@media (prefers-contrast: high) {
  :root {
    --border-color: #000000;
  }
  
  [data-theme="dark"] {
    --border-color: #ffffff;
  }
}

/* Print styles */
@media print {
  .header,
  .footer,
  .theme-toggle,
  .generate-btn,
  .clear-history-btn,
  .toast {
    display: none !important;
  }
  
  .main {
    padding: 0;
  }
  
  .card {
    box-shadow: none;
    border: 1px solid #000;
    page-break-inside: avoid;
  }
}